PINUS LARICIO 163 



4. Describe variations in the diameter of the trunk. 



5. Do you find prominent swellings (buttressing roots) 

 at the base of the trunk? If so, suggest their 

 possible advantage to the tree. 1 



6. Describe the outline of the crown as flat, conical, or 

 cylindrical. 



7. Describe the appearance of the bark. 



8. Note that the lateral branches appear to be given 

 off in whorls, or circles, at regular intervals along 

 the trunk. Observe closely and state whether 

 these are true whorls (i.e., the component branches 

 in exactly the same horizontal plane), or pseudo- 

 whorls (i.e., the branches not really in the same 

 plane). 



9. Do you find enlargements on the under side of the 

 larger limbs at the base? Suggest any advantage 

 this may be to the limb; the conditions resulting 

 in their formation. 



10. Draw a diagram illustrating all points observed 



under C, 1-9. Make the trunk 15 dm. high. 

 D. The Vegetative Branches: 



1. In specimens furnished, note the two kinds of vege- 

 tative branch: The main or "long" branch, bear- 

 ing scale-like leaves, and, in the axils (upper angle 

 made by the leaf with the branch that bears it) of 

 these scales, the dwarf branches, bearing the foliage- 

 leaves or pine "needles." In what does the long 

 branch terminate? 



2. The Long Branch. 



(a) Describe the arrangement (spiral) and dis- 

 tribution of the dwarf branches on the long ones. 



(b) Note the rings of dry bud-scales or scale-scars 



conditions favoring the formation of buttresses should be dis- 

 cussed in class. 



